Dana named the dog Queequeg after the character in Herman
Melville's 1851 novel "Moby Dick." The dog briefly appeared in
episode No. 60 "War of the Coprophages."

On episode No. 70 "Quagmire" while Scully and her partner Mulder
(David Duchovny) investigated a series of deaths linked to a lake
monster called Big Blue in the Blue Ridge Mountains of Georgia, her
dog ran off into the woods. Scully chased after Queequeg but only
found the dog's empty collar tangled in a fishing line. A little
later a rogue alligator was killed. It was the dog's assassin
(or maybe it was Big Blue).